Research On The Effects Of Processed Cheese Processing And Its Formula On The Product Quality

Processed cheese is the member of the cheese's family. It is rich in calcium, lacto protein, milk fat, vitamin and minerals, but low level of lactose, which is suitable for lactose intolerance people. Compare with the nature cheese, processed cheese has its advantages as follow: it has gentle flavour, more accepted for the Chinese; It has good preservability; The source of raw material can be obtained widely; Low cost for producing processed cheese. So it arouses great attention in the dairy industry, and this dissertation is focus on the demand of processing equipment which is lack of in China, and dependenting on the equipment, systematic researches of processing processed cheese have been carried out.The main contents are as follows:(1)Do research on processed cheese's processing technology, optimize and improve the equipment;(2)Formulate the emulsifying salts; choose the suitable emulsifying salts for producing processed cheese;(3)Do the research on the microstructure, rheology, secondary structure and water distribution of processed cheese with different emulsifying salts;With those experiments, the conclusions are as follows:(1)According to the assay and analysis, the parameters of emulsify salts'proportion, amount of water addition, ratio of raw materials, melting temperature and mixing speed are 3%, 10%, 3:4:3, 85℃and 1200rpm respectively, and 3.5%, 10%, 3:5:2, 75℃, 1500rpm respectively. Those two are the best combinations for producing slice processed cheese. The viscosity increase radically from 45℃.So it is regarded as the best temperature for aseptic canning.(2)With the quadratic orthogonal rotating regression design and response surface methology, the effect of operation parameter and varieties of additions on processed cheese have been studied and analysised. The results indicate that the best combination for slice processed cheese: the ratio of fresh cheese, proportion of emulsifying salts, melting temperature and mixing speed are 60%, 1.5%, 90℃, 1200rpm respectively.(3)According to the mixing experiment, the best combination of all conditions can be found. The best formulation for slice and sheet cheese is STTP: TSC: TSPP: DSP=35:35:20:10.(4)The processed cheese made with 3% emulsifying salts has better quality than with 1%, it can be seen from the scanning graph and analysis from rheology. When the temperature is at 60℃and 80℃, the viscosity decrease little, but when it comes to 35℃, it changes a lot. On the whole, when the shear rate is increasing, the shear stress is increasing. Storage modules are always bigger than loss modules. The processed cheese is to be solid.(5)With FT-IR flourier transform infrared spectrometer and low field NMR, processed cheese made with different emulsifying salts have been analysised. The results indicate that the secondary structure of protein still existence such asα-helix,β-sheet, randon coil andβ-turn, but different in proportion.It can be seen from the processed cheese's relaxation graph, the processed cheese's relaxation lifetime has four parts. They are 0.01ms~1ms,1ms~10ms,10ms~100ms and over 100ms. The main part is 10ms~100ms, others are few. It means that the water in processed cheese is mainly bound water with milk fatglobule membrane and milk protein, also, well-distributed.